PH Indicator | MCQs

Explanation

• When blue litmus paper is dipped in an acid, it turns red.
• This is because the acid changes the color of the litmus paper from blue to red.

Note: When red litmus paper is dipped in a base, it turns blue.

Explanation

• Phenolphthalein is a pH indicator that changes color in response to changes in acidity or basicity.
• In an acidic medium, it is colorless, and in a basic medium, it turns pink.

Explanation

Indicators are colored organic compounds that change color depending on the pH of the solution.

Common examples include litmus, phenolphthalein, and methyl orange.

Explanation

Methyl orange is a pH indicator that turns yellow in alkaline solutions.

In acidic solutions, it appears red, but in basic or alkaline solutions, it changes to yellow.

Explanation

Rose petals act as a natural pH indicator.

They turn blue in alkaline (basic) solutions due to pigment changes.

Explanation

Phenolphthalein is colorless in acidic and neutral solutions but turns pink in an alkaline medium.

This happens because, in a basic solution, phenolphthalein loses H⁺ ions, forming its negatively charged phenolate ion, which gives the pink color.

Explanation

A litmus test is a phrase that originated from the use of litmus paper in chemistry, which changes color in response to certain conditions.

In a broader sense, a litmus test refers to a situation, event, or factor that clearly indicates whether a particular approach, idea, or decision is effective, valid, or acceptable.

It's a decisive test that provides clear evidence or proof.